Convert DMG to IPSW

A restore performed through Finder, Apple Devices, Apple Configurator, or older iTunes needs an .ipsw firmware package, while some older Apple downloads arrive as .dmg disk images. The usual solution is to extract an existing IPSW from the DMG, not to convert the disk image itself.

What the DMG format is

DMG is Apple's disk-image format for macOS. It represents a mountable filesystem volume and can contain software installers, recovery utilities, firmware files, or other files. macOS uses Disk Utility and hdiutil to create and mount DMG images; Windows users commonly inspect them with 7-Zip or dedicated DMG extraction software.

A DMG is a container, not an iPhone or iPad firmware package. It may contain an IPSW file, firmware payloads, or unrelated Mac files. Changing .dmg to .ipsw does not change the format.

What the IPSW format is

IPSW is Apple's firmware package format for iPhone, iPad, iPod touch, Apple TV, Apple Watch, and other Apple devices. An IPSW is generally a ZIP-based archive containing device-specific manifests, signed firmware payloads, restore images, and often additional DMG files.

Finder, Apple Devices for Windows, Apple Configurator, older iTunes, and utilities such as idevicerestore use IPSW files for updates and restores. The package must match the device model, and Apple must normally still be signing the relevant firmware version. A ZIP archive with an .ipsw extension is not automatically a usable restore package.

How to extract or repackage the files

1. Check the DMG before attempting conversion. On macOS, inspect and attach it read-only:

hdiutil imageinfo source.dmg
hdiutil attach -readonly source.dmg

Open the mounted volume in Finder and search for an .ipsw file. If it exists, copy that file unchanged. Detach the volume afterward with hdiutil detach /Volumes/VolumeName.

2. Extract the image on Windows when necessary. Open the DMG with 7-Zip and extract its contents to a local folder. 7-Zip does not support every DMG filesystem, compression method, or encryption scheme; use macOS and hdiutil when it cannot read the image.
3. Identify a complete firmware package. A candidate IPSW normally has files such as BuildManifest.plist, Restore.plist, device firmware images, and other Apple-supplied payloads at its archive root. A macOS installer, a generic recovery volume, or a lone file such as RestoreRamDisk.dmg is not a complete IPSW.
4. Repackage only a verified complete package. If the extracted directory already contains the complete IPSW contents, create a ZIP from the files inside that directory, not from the parent directory:

cd extracted-firmware
zip -r -X ../candidate.ipsw .

In 7-Zip, select the firmware files, choose Add to archive, select the ZIP format, and rename the resulting .zip file to .ipsw. Keep manifests and payloads at the archive root. This is repackaging, not firmware conversion.

Use the resulting file only if its contents came from a genuine, complete Apple firmware package. In Finder or Apple Devices, hold Option on macOS or Shift on Windows while selecting the device's restore or update command, then choose the IPSW.

Compatibility and quality limits

No converter can create missing firmware, manifests, restore metadata, device compatibility, or Apple's signing authorization. Extracting files from an inner DMG and compressing them again cannot turn incomplete firmware into a valid IPSW. Repackaging can also fail if files were omitted, placed at the wrong archive level, or taken from different firmware builds.

The safest source is a firmware package downloaded through Finder, Apple Devices, or Apple Configurator. An IPSW catalog such as ipsw.me can help locate device-specific downloads, but verify the file and firmware status before restoring. There is no reputable online service that can reliably convert an arbitrary DMG into a valid IPSW; online upload is also unsuitable for large firmware images and potentially sensitive recovery files.